Welcome to HVAC-Talk.com, a non-DIY site and the ultimate Source for HVAC Information & Knowledge Sharing for the industry professional! Here you can join over 150,000 HVAC Professionals & enthusiasts from around the world discussing all things related to HVAC/R. You are currently viewing as a NON-REGISTERED guest which gives you limited access to view discussions

To gain full access to our forums you must register; for a free account. As a registered Guest you will be able to:

Participate in over 40 different forums and search/browse from nearly 3 million posts.

Not trying to start a war here, but why get digital gauges? I know everyone has their preferences, but digital gauges seem like total overkill to me. I could buy a bag full of other quality tools for the price. Maybe I'm missing something -- do they do something that a regular gauge doesn't do or are they just easier?

Not trying to start a war here, but why get digital gauges? I know everyone has their preferences, but digital gauges seem like total overkill to me. I could buy a bag full of other quality tools for the price. Maybe I'm missing something -- do they do something that a regular gauge doesn't do or are they just easier?

Digital gauges do make life a ton easier....not to mention they last longer than analog from what I've heard.

But how do they actually get accurate A/C superheat readings from the gauge port?? Here in some of the Chicago high rises, the temp leaving the evap can be quite different than the temp at the service port of the condensing unit, especially with a crappy install and broke down suction insulation. Again, not arguing, just curious with the preference. I never heard of anybody wanting digital gauges until I joined this forum.

But how do they actually get accurate A/C superheat readings from the gauge port?? Here in some of the Chicago high rises, the temp leaving the evap can be quite different than the temp at the service port of the condensing unit, especially with a crappy install and broke down suction insulation. Again, not arguing, just curious with the preference. I never heard of anybody wanting digital gauges until I joined this forum.

Getting superheat and subcool readings with a digital set is the same as getting readings using analog, you still have to hook temp sensors to the line...the difference is all of your readings are on one screen, in digital numbers, and you are not carrying several tools around for the same job.

Digital gauges can be and claim to be more accurate than analogs, showing real time changes that are going on in your system, and showing the readings that would be between each hash mark on your analogs.

But how do they actually get accurate A/C superheat readings from the gauge port?? Here in some of the Chicago high rises, the temp leaving the evap can be quite different than the temp at the service port of the condensing unit, especially with a crappy install and broke down suction insulation. Again, not arguing, just curious with the preference. I never heard of anybody wanting digital gauges until I joined this forum.

Some guys might tell you "Set your superheat for 12 degrees at the bulb" or some such number like that. This, to me, can be very misleading information. You want to know what the compressor manufacturer recommends for Superheat at the Compressor. As long as your compressor is operating within mfr's specs, the rest will be easy. Or easier, anyway. Set your Superheat to keep the compressor happy.

The views and opinions posted here are my own. They do not reflect the corporate policies of my employer and will most likely get me fired at some point.

I see what you're saying. That is true, and usually if you set the correct superheat out of the evap then the compressor is good, too. Checking both would be the best way. If you're using just the temp at the service port then that doesn't give you an accurate idea of what's boiling off in the evaporator.

Not trying to start a war here, but why get digital gauges? I know everyone has their preferences, but digital gauges seem like total overkill to me. I could buy a bag full of other quality tools for the price. Maybe I'm missing something -- do they do something that a regular gauge doesn't do or are they just easier?

If I banged my analogs half as hard as I feel comfortable banging my digitals, I think I would be buying one if not two replacement gauges for my manifold. The reality is that sets of digitals are more rugged than what we have been using, analogs. The replacement cost of gauges that wear out or get bumped out of calibration is what makes digitals cheaper, or at least equivalent over the long run. Accuracy is way better than your standard class b gauge. Couple that with the fact that taking your superheat and subcooling readings are so easy to take, I do it on every system I hook up to. It's easier than putting the hoses on. I can do the math the manual way, but if your just getting started you'll have to buy a temp probe and you only get as many readings as you do the math. Once you're spoiled by real time readings, you won't want to go back.

On systems that I install I put a suction fitting next to the evaporator. Some of the systems have 50 to 100 ft line sets. If the pipes are sized right the pressure doesn't change by more than a few psi. Engineerdave is right about the compressor superheat. It has to be within certain limits. Some recommend between 20-30 at the compressor.